Over the past two weeks, Democrats have begun to acknowledge that they have virtually no evidence demonstrating meaningful collusion between the Trump campaign and the Russian government. They proclaim that circumstantial evidence shows ties between Trump staffers and President Vladimir Putin -- former Trump campaign manager Paul Manafort and former Trump advisor Roger Stone allegedly had significant contacts with the Russians. But to this point, they've got nothing.

Meanwhile, the FBI director and head of the National Security Agency announced that they had no evidence that Trump Tower was wiretapped by former President Obama. Mike Rogers, the NSA head, agreed that any accusations of British intelligence involvement in Trump wiretapping is "ridiculous." Republicans point to the fact that there were multiple media reports of Trump associates being caught on wiretap. But to this point, they've got nothing.

Scandals that catch fire require two elements: first, confirmation of a widely held suspicion about a politician's character; second, actual evidence of nefarious behavior. Hillary Clinton's email scandal damaged her significantly because of her long record of untrustworthy behavior, including destruction of records. Bill Clinton's sex scandal damaged him because he had a long history of lying about his sexual conduct.

Other scandals simply never gained steam because they lacked the requisite plausibility, even if the evidence was sufficient. Yes, the IRS should have damaged President Obama. But the central contention that Obama used government as an instrument to target his opposition never took hold of the public imagination. Sure, Iran-Contra should have severely tarnished President Reagan. But Americans didn't buy the notion of Reagan as a great international manipulator. In short, politicians we trust more are less likely to suffer from severe scandal.

And herein lies the problem: In an era in which half of the population will believe virtually everything about the other side, we're primed for scandal all the time. The tinder of scandal is dry, and everyone is just waiting nervously for a lit match to set the blaze. That means a whiff of scandal pervades nearly everything. Otherwise-innocuous behavior seems laden with sinful potential. And those who claim wrongdoing about those on the other side gain additional credibility no matter the evidence of what they claim.

That means the conspiracy theorists gain ground while honesty loses. Those on the left willing to accuse President Trump of Kremlin connections sans evidence earn the love and support of those on their own side of the aisle; and those on the right willing to humor Trump's most extreme claims about Obama's wiretapping gain clicks and admiration on their side. The result: Those who suggest that we wait for evidence are seen as gullible, naive.

In this context, the space for rational conversation shrinks down to a thimble. Instead of the left dismissing President Trump's stupidities as stupidities, Trump becomes a nefarious character seeking doom; instead of the right acknowledging that intelligence could have swept up some Trump contacts in its pursuit of Russian interference, the entire intelligence community becomes a big blob of statist corruption. No mistake is honest; every action must be interpreted in the darkest possible way.

If this leads to an American return to smaller government -- hey, we can't trust anybody anyway, so let's stop handing them power -- this new paranoia might be acceptable. But it won't. Instead, Americans seems bound and determined to hand power to those on each side who are most apt to identify the nefarious intentions of those on the other side, with or without evidence. That's a recipe for not only polarization but also political breakdown.